Improved large-area forest increment information in Europe through harmonisation of National Forest Inventories

14 Pág.Consistent knowledge about the increment in European forests gained amplified importance in European policies and decision processes related to forest-based bioeconomy, carbon sequestration, sustainable forest management and environmental changes. Until now, large-area increment information from European countries was lacking international comparability. In this study we present a harmonisation framework in accordance with the principles and the approach established for the harmonisation of National Forest Inventories (NFIs) in Europe. 11 European NFIs, representing a broad range of increment measurement and estimation methods, developed unified reference definitions and methods that were subsequently implemented to provide harmonised increment estimates by NUTS regions (Nomenclature of territorial units for statistics of the European Union), main forest types and tree species groups, and to rate the impact of harmonisation measures. The main emphasis was on gross annual increment (GAI), however, also annual natural losses (ANL) and net annual increment (NAI) were estimated. The data from the latest available NFI cycles were processed. The participating countries represent a forest area of about 130 million ha, and 82% of the European Unions’ (EU) forest area, respectively. The increments were estimated in terms of volume (m³ year−1, m³ ha−1 year−1) and above-ground biomass (t year−1, t ha−1 year−1). The harmonised GAI volume estimates deviate in a range of +12.3% to −26.5% from the estimates according to the national definitions and estimation methods. Within the study area, the harmonised estimates show a considerable range over the NUTS regions for GAI, from 0.6 to 12.3 m³ ha−1 year−1, and 0.8–6.4 t ha−1 year−1, of volume and above-ground biomass, respectively. The largest increment estimates are found in Central Europe and gradually decrease towards the North, South, West and East. In most countries coniferous forests show larger increment estimates per hectare than broadleaved forests while mixed forests are at an intermediate level. However, in some instances, the differences were small or mixed forests revealed the largest increment estimates. The most important tree species groups in the study area are Pinus spp. and Picea spp., contributing 29% and 26% of the estimated total GAI volume, respectively. The shares of the prevalent broadleaved species are smaller with contributions of 9%, 7% and 6% by Quercus spp., Fagus sylvatica and Betula spp. The results underline the importance of harmonisation in international forest statistics. Looking ahead, harmonised large-area increment estimation is pivotal for accurate monitoring and evidence-based policy decisions in the changing context of future forest ecosystems dynamics, management strategies and wood availability.This research was supported by the Specific Contracts No. 20 and 21 “Use of National Forest Inventories data to harmonise and improve the current knowledge on forest increment in Europe” in the context of the “Framework contract for the provision of forest data and services in support to the JRC activities and applications on forest resources (Contract Number 934340)” of the Joint Research Centre of the European Commission.Peer reviewe

Risk of the wind damage to the forests in Poland on the basis of a stand damage risk model

On the basis of the wind damage risk model for forests using the data of the State Forests Information System, the stand damage risk factor Wr for each of the 430 forest districts in Poland and the threat measure Ms for a given forest district were determined. The measure of threat to forest Ms for a forest district is a methodical basis for assessing the potential damage to forests in Poland. Its value ranges from 8.1% for the Brzózka Forest District to 48.9% for the Ujsoły Forest District (fig. 1), giving the average value of 24.6% and standard deviation of 7.03%. The measure Ms was the basis for differentiating the levels of threat of wind damage to forest for forest districts. Level 1 (Ms≤10%) indicates low threat, level 2 (10%40%) – very high threat. Low threat to forests was found only in two forest districts located in the western part of the country. 113 forest districts, which form large concentrations particularly in western and central Poland, are exposed to an elevated threat. Most forest districts (233) are classified to a group of moderate threat. They are located across the country and are mostly concentrated in the northern and southern regions of Poland. 71 forest districts exposed to high threat are concentrated in the south of Poland in the Carpathians and the Sudetes, with scattered presence in the north of the country. Most of the 11 forest districts with a very high threat to forests are located in the mountains (tab., fig. 1). For the forest districts with a particularly high and very high threat, new silvicultural procedures and the basis for decision making in the field of forest management should be developed to reduce the risk of damage to forest

Method of standardization of administrative costs of forest districts based on the management difficulty level

The article presents a method to standardize the administrative costs of forest districts using the management difficulty level index (STG). The scope of the study included the development of a revised structure of the STG for forest districts, comparison of the substantive and statistical factors that shape the level of administrative costs being incurred by forest districts with partial indicators that form the STG index, the development of the methods for determining the standard administrative costs of forest districts using the STG, and the selection of a method to be applied in the financial and economic practice of the State Forests. The source data for the administrative costs incurred by forest districts, as well as the data on the natural−forest conditions and annual economic tasks of the forest districts were obtained from the State Forests Information System databases for all the forests districts in Poland and from the Bureau for Forest Management and Geodesy. Information about the social environment of the forest districts was obtained from the Local Data Bank of the Central Statistical Office in Poland. In the methodological assumptions concerning the development of a method for shaping the level of administrative costs of the forest districts, two variants were adopted. The structuring of the STG for forest districts, as a tool to standardize administrative costs of forest districts, adopts the 'sum of relative values' method, where relative values of individual partial indicators (six simple and five complex ones) are obtained by dividing the absolute values of a specific indicator by the maximum value of this indicator for the whole population The obtained results of calculating the level of standard administrative costs of forest districts in two variants were similar. For the sake of clarity, simple mathematical formulas, and the ease of use by organizational units of the State Forests, the administrative cost standardization method based on the calculated average value of 1 item of the STG for forest districts per a given administrative cost group in the State Forests was used to build a makeshift of the State Forests plan for 2014−2016

Dieback of Norway spruce stands in the Beskid Zywiecki Mts.

In the Beskid Żywiecki, the combination of abiotic, biotic and anthropogenic factors unfavourable for the growth of trees led to the dieback of spruce stands. The intensification of this process began after the hurricane in November 2004, followed by years of negative climatic water balance. The deterioration of tree growth conditions occurred after the drought in July 2006 and damage caused by the Kyril hurricane in January 2007. The weakened spruces were attacked by the bark beetles, the outbreak of which caused a massive dieback of spruce stands. In order to assess the volume of harvested timber in years 2004−2016, the volume of allowable cut (model volume) was calculated from the stand growth model for each forest district of Beskid Żywiecki. The comparison of the volume of harvested timber with the model volume allowed to determine the rate of dieback of spruce stands. The volume of harvested timber in 2007−2009 exceeded the model volume even 2.5 times. The cuts included mainly deadwood, wind−broken and wind−fallen trees, while the harvest of live trees was scarce. In the period 2010−2013, the harvested volume of live trees accounted for 50−70% of the model volume, the volume of deadwood in the same period was ca. 100% and additionally the volume of blown−down timber after the hurricane was 20−40% of the model volume, which taken together accounted approximately to 200% of the model volume. The execution of such harvesting operations, including silvicultural tasks, did not allow to carry out optimal forest management. The period 2010−2013 saw a downward trend. It was disrupted by the hurricane in December 2013, after which the volume of harvested timber, consisting mainly of wind−broken and wind−fallen trees, increased to 280% of the model volume. Again, the high volume of harvested timber was noted in 2016, (ca. 220% of the model volume). The process of damage to spruce stands in Beskid Żywiecki is likely to continue. A decline in its intensity may occur in the absence of old stands, which to a large extent already takes place in the forests of the Węgierska Górka Forest District. Currently, the most threatened by wind are forests in Ujsoły, Jeleśnia and Nowy Targ forest districts. The least threatened are forests in the Węgierska Górka. This forest district and in the future the remaining forest districts of Beskid Żywiecki, will face enormous challenges to obtain high yield and appropriate species composition

Forest area in Poland based on national forest inventory

Forest area in Poland is annually evaluated as a part of public statistics research. However, this information is based on land use resulting from Land and Property Register (LPR). Delays in the reclassification of afforested land, as well as the natural expansion of trees on abandoned agricultural lands, observed over the last decades, caused that information from LPR becomes unreliable. In many countries forest area is assessed within the National Forest Inventories (NFIs) based upon systematic grid of sample plots. NFI in Poland has been performed since 2005, in 4×4 kilometre grid with clusters consisting of five plots. Until 2014 measurements were made only on these sample plots which were located in forest according to LPR records. Within the 3rd NFI cycle (2015−2019) the areas fulfilling the criteria of forest definition, but located on non−forest land referring to LPR, has become the object of study. The aim of this work is to present statistical approach for evaluation of forest area using NFI cluster sampling data. Additionally, results from two year measurements (2015−2016) were analysed and compared with LPR data. Attributes of NFI plots allow to apply national forest criteria as well as the land use and land cover thresholds recommended by Food and Agriculture Organization of the United Nations or Kyoto Protocol. Our research shows that forest cover in Poland is in the range of 32.8−33.0%, depending on forest definition used, and is almost 3% higher than official LPR data (30.1%). The standard error of forest cover, based on two years NFI data is 0.44. Thus, with 95% probability the true value of this parameter lies between 31.9 and 33.7%, while country thresholds of forest definition are used. Additionally it was assessed that using the entire NFI cycle data the standard error of forest cover should be lower i.e. less than 0.3. The National Forest Inventory seems to be an appropriate tool for monitoring forest area in Poland

Dynamics of tree mortality in the Sudety Mts. in years 2002-2018

The aim of the study was to present two issues concerning forests in the Sudety Mts. (SW Poland): 1) the process of tree mortality in individual years in the period between 2002 and 2018, as well as 2) the analysis of the radial growth of the main tree species (i.e. spruce, larch, beech, fir and Douglas fir). The intensity of the process of tree mortality is evidenced by the volume of wind−broken or wind−fallen trees and deadwood. The record volume of post−hurricane wood was harvested after the hurricane ‘Cyril’ (January 2007). The volume of wood removed in 2007−2008 amounted to 1.4 million m3. Quite a high share of wind−broken and wind−fallen trees in the volume of harvested wood raw material concerned the years 2002, 2003, 2006, 2008 and 2018. In the latter year, the damage was caused by the hurricane ‘Grzegorz’. The record removal of deadwood occurred in 2016 following an exceptionally severe drought in the 2015 growing season. The high volume of deadwood in 2017 and 2018 was augmented by quite a high volume of wind−broken and wind−fallen trees. Spruce and larch showed the strongest response to severe drought in 2015 by lowering the increment in diameter and producing a narrow layer of latewood, while the response of beech and Douglas fir was the slightest. No such response was found in fir. The main tree species in the Sudetes is spruce, which quickly disappears from this area. It is necessary to look for such species of trees that might replace spruce, i.e. species more suitable to changing climatic conditions, such as beech, oak, ash, sycamore, pine and larch – but also fir and Douglas fir. The latter two species show a high tolerance to changing climatic conditions, and a high potential in the production of wood

Potential climatic range for Abies alba Mill. in Poland

Numerous examples of silver fir stands growing outside its geographical range in northern Poland suggest that this species could be used in a greater extend in creation of managed forest stands. Climatic conditions could potentially constrain the use of this species in some parts of country. The objective of this work was to determine the potential climatic range of Abies alba in Poland. The bioclimatic envelope models were used to identify areas in which selected climatic variables show the same range of variability as observed within natural range of this species. Climatic data with 10' spatial resolution were used. The outcome of the analysis depends to large extent on the demarcation of natural range (in which the variability of tolerable climatic conditions is assessed). The model basing on the climatic conditions in whole natural range of silver fir in Europe suggest that almost whole area of Poland is suitable to fir, but models basing only of climatic conditions in Polish part of its natural range are much more conservative. In the last case the difference in extent between natural range and potential climatic range was smaller. As genetic variability of Polish fir populations is rather low, they are supposed to have constrained adaptative abilities. Forest managers should not focus on planting silver fir outside its natural range, but they rather should consider reintroduction of fir in parts of natural range from where it retreated in 20th century

Methods of standardisation of the unit costs of selected silvicultural works

The article presents methods for standardizing the costs of the silvicultural treatments (renewals and afforestation, corrections and additions, tending). Our scope included the statistical determination of factors shaping the costs of selected works, elaborating methods of their standardization, assessment of these methods suitability for determining standard unit costs of selected silvicultural works, and selection of the method for application in the financial system of the State Forests. The data were obtained from the database of the State Forests Information System for all forest districts in the country. Information about the social background of forest districts was obtained from the Local Data Bank. Initially we analysed factors shaping the costs of forest works. The first developed method was based on the grouping of forest districts with similar natural conditions described by the forest habitat types, which are the main factor shaping the costs of silviculture. The other method consisted of technological models for the field−works using the time−consumption catalogues used in the State Forests. Each of the developed methods is characterized by specific disadvantages and advantages. The first method determines the standard costs on the basis of historical data. The use of data incurred by forest districts in previous years has a major disadvantage, as they may contain results of poor efficacy from previous periods. However, the creation of groups of forest districts with similar natural conditions by organizational units from different regions of the country with different economic and social conditions, as various regional directorates of the State Forests pursuing a specific policy on the amount of rates for services performed by forest companies limits the disadvantages. The main advantage of the other method is that it is not based on the historical data. This method also gives the forest district management the opportunity to compare rates for services provided by forestry companies with the economic environment of the forest district, thanks to the use of the average monthly gross wages in administration districts. The disadvantage of this method is the lack of source data (time−consumption) from forest districts planning costs in natural units and applying long−term agreements with forestry services companies. Full assessment of the proposed methods will be possible after comparison of standardized costs calculated by different methods with actual values

Management Difficulty Index in the forest ranges of the State Forests

The paper presents the calculations of the Management Difficulty Index (STG) for forest ranges in the State Forests. The calculations were made on the basis of the characteristics of the management conditions and the scope of tasks for all forest ranges in the country in 2009. The usefulness of the STG index was proven in the management practice of the State Forests